Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disorder characterized by premature senescence. Affected children appear normal at birth, but within a year develop characteristic features of old age. The majority of HGPS children die from cardiac disease at an average age of 13 years. Genetic studies have identified a mutation in the lamin A/C (LMNA) gene in 18 classical HGPS cases. The mutation results in the production of a mutant lamin A protein with an internal deletion. The mechanism by which the mutated HGPS lamin A protein leads to accelerated aging is unknown. Lamin A appear to maintain nuclear structure and function through a set of specific protein interaction with other cellular factors. I therefore hypothesize that expression of the mutant HGPS lamin-A protein results in premature aging as a consequence of the altered composition and function of lamin A-containing complexes within the nucleus. To test this hypothesis, in Aim 1 I will first define the cellular growth properties of HGPS fibroblast to identify the cellular pathways responsible for the limited life span of these cells in culture. Then in aim 2, I will employ biochemical approaches to identify and characterize the proteins associated with wild type and mutant HGPS lamin A. [unreadable] [unreadable]